The Connection Between Sleep Apnea and High Blood Pressure

by | May 13, 2021

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You may not know it, but sleep apnea and high blood pressure have more in common than you think. 

These two conditions are dangerous on their own, but they can be a real nightmare together. High blood pressure, also known as hypertension, is one of the most common health problems in the United States, with nearly 1 out of 2 American adults— or more than 100 million people— suffering from it.

We all know how it feels to wake up after a restless night of sleep— you may feel groggy and unfocused, maybe you even have a headache. But what you may not realize is that your poor sleep quality or short sleep duration may also be affecting your heart health.

To better understand the connection between high blood pressure and obstructive sleep apnea (OSA), let’s begin by taking a look at some key points about hypertension and how it affects your body.

What is Hypertension?

Your blood pressure is created by the force of blood pushing against your artery walls— hypertension occurs when this force is too strong. Because of this, your heart has to work harder and becomes strained and unable to function at its optimal capacity.

There are multiple types of hypertension, some of which include:

  • Pulmonary Hypertension/Pulmonary Arterial Hypertension (PAH)
  • Refractory Hypertension
  • Systemic Hypertension
  • Resistant Hypertension

You’re likely familiar with your doctor’s blood pressure monitoring tests, and the tight squeeze they put on your arm as it records your results. The two numbers on your results are your systolic blood pressure and your diastolic blood pressure, with systolic pressure on top and diastolic pressure on the bottom.

  • Your systolic blood pressure indicates how much pressure your blood is exerting on your arteries while your heart beats.
  • Your diastolic blood pressure is the measure of the rest between your heartbeats.

A normal, healthy blood pressure reading is around 120/80 or below— while it’s normal for your blood pressure to fluctuate during the day, consistently elevated blood pressure is not normal and may indicate hypertension as well as additional complications.

How Hypertension Affects Your Body

High blood pressure contributes to hundreds of thousands of fatalities each year, with nearly half a million deaths in the United States alone. According to the Center for Disease Control, Tennessee has a high prevalence of hypertension in adults ages 20 and older, with an age-adjusted prevalence between 32 and 38.6 percent.

Left untreated, hypertension can damage your heart and contribute to severe health issues that can lead to a disability or even premature death. Some of these include:

  • Cardiovascular Disease
  • Atrial Fibrillation
  • Aneurysms
  • Heart Attacks or Failure
  • Vision Loss
  • Stroke
  • Kidney Disease or Failure

Risk Factors for Hypertension

Age is a common risk factor for hypertension, as well as gender and family history. And while it’s a common health condition among American adults, hypertension does not have any visible symptoms or signs of illness. This is why it’s sometimes called “the silent killer.”

Hypertension is strongly connected to conditions like heart disease, heart failure, stroke, and even erectile dysfunction. These conditions are also linked to sleep-disordered breathing, also referred to as sleep apnea. Research indicates up to 50% of people suffering from hypertension also have sleep apnea, which is why anyone struggling with high blood pressure can benefit from a sleep test.

The good news is that hypertension is highly treatable with a healthy diet, productive sleep habits, and exercise. If your hypertension doesn’t respond well to these lifestyle changes or medication, getting a sleep test to see if you have undiagnosed sleep apnea is important.

Related: Why the “Loud Killer” is 2-3 Times as Dangerous as the “Silent Killer”

Hypertension and Poor Sleep

There is a clear link between a person’s sleep patterns and their risk for high blood pressure. A study by the Journal of Sleep Medicine found that people who get less than six hours of sleep each night were 20 percent more likely to have hypertension. 

A study by the journal Hypertension showed that people who get less than six hours of sleep each night were shown to have higher blood pressure the next day, as compared to those who got the recommended amount the night before. This pattern, continued over time, only works to compound the issues and increase the risk for hypertension.

By getting the appropriate sleep quality as well as quantity each night, it’s possible to avoid this issue. However, doing this isn’t so simple if you also have a sleep disorder.

As mentioned earlier, about half of people experiencing hypertension have obstructive sleep apnea as well. Hypertension doesn’t cause sleep apnea, but there is a connection between the two.

What is the Connection between Sleep Apnea and Hypertension?

In addition to the other health conditions hypertension contributes to, high blood pressure can also make sleep apnea symptoms worse, and vice versa. These two conditions have a cyclical effect upon each other, which is concerning if you happen to have both.

Obstructive sleep apnea restricts your breathing by blocking your airways. The blocked airway restricts how much oxygen enters the body, which puts added stress on your cardiovascular system.

In what’s known as blood pressure dipping, blood pressure can lower between 10 and 20 percent each night in healthy individuals. Those with obstructive sleep apnea experience dips of less than 10 percent, which puts them at higher cardiovascular risk.

Related: What Makes Sleep Apnea Worse? 8 Things to Watch Out For

Sleep Apnea Forces the Heart to Work Harder

The airway blockages created by obstructive sleep apnea cause your blood pressure to increase, because your heart is working harder to get oxygenated blood flowing through your body.

While you’re asleep, sleep apnea triggers the brain to pump more blood to key areas like the brain and heart. This puts added pressure on your artery walls and spikes your blood pressure higher than if you were breathing normally while asleep.

Sleep Apnea Creates Norepinephrine Spikes in the Body

When your airway is blocked or constricted at night when you’re asleep, your body must find a way to open up the airway so you can breathe. It does this by releasing norepinephrine, also sometimes referred to as adrenaline. Norepinephrine—norepi— is the main “awake” neurotransmitter in the brain, and it arouses the brain to signal the throat to open up and let air in.

Although most people don’t actually wake up, the arousal is enough to increase the muscle tone in the throat and return it to how it normally is during the day. Unfortunately, the norepinephrine release also creates a “fight or flight” response in your body that increases your heart rate, as well as your blood pressure.

Its release is so effective at raising blood pressure in the body, norepinephrine is used in the ICU to treat people in shock and at risk of death for low blood pressure. This is because it’s the most powerful agent we know of to increase blood pressure.

The more frequently you have these respiratory events at night, the more norepinephrine you’re going to release, and the more your blood pressure will rise. This can make keeping blood pressure under control exceedingly difficult if you have undiagnosed sleep apnea or aren’t properly treated.

When someone with obstructive sleep apnea stops breathing during sleep, or their breathing is restricted and they struggle to breathe, resuming breathing will spike blood pressure as well. The cycle of stopping and resuming breathing can also cause a person to wake up during the night, which can spike blood pressure even further.

Does Sleep Apnea Treatment Help High Blood Pressure?

Thankfully, yes! Research indicates that treating sleep apnea can lead to dramatic improvements for those suffering from hypertension. One of the most common and effective treatments for OSA patients, CPAP therapy— continuous positive airway pressure — not only improves sleep quality, but also improves blood pressure in those with hypertension.

One study, led by Dr. Claudia Korcarz of the University of Wisconsin’s Atherosclerosis Imaging Research Program in 2014, looked at the impact CPAP machines have on blood pressure. The results showed CPAP therapy dramatically reduced high blood pressure in adults with obstructive sleep apnea.

After three months of CPAP treatment, OSA patients who used their machine for approximately 6 hours each night reported both reduced hypertension and increased artery size.

Two more observations from the study also pointed to how important positive airway pressure was in regulating hypertension. Namely, participants who stopped using their CPAP machines had blood pressure readings begin to increase after only one week.

Participants who didn’t stop treatment completely, but also didn’t follow their CPAP treatment consistently, demonstrated no significant improvements in hypertension. These participants averaged about 2.5 hours of use each night or less.

How Does Sleep Apnea Treatment Affect Blood Pressure?

CPAP treatment doesn’t actually lower blood pressure levels, but it prevents the events that lead to blood pressure increasing at night. By removing the airway blockages that lead to arousals during the night, CPAP prevents the production of nighttime norepinephrine, and in the process stops blood pressure from rising to abnormal levels.

A telltale sign that severe OSA is making your hypertension worse is when many of the normal solutions for treating high blood pressure, such as getting more exercise and implementing a healthier diet, don’t work. In this case, especially if you snore during the night which is a major sign of airway blockage, there’s a strong likelihood your hypertension won’t improve unless your sleep apnea is treated. This is where seeing a doctor about your untreated OSA becomes especially important.

Your quantity and quality of sleep are directly related to your blood pressure levels, and it’s important to get a good night’s sleep every night if you wish to maintain healthy blood pressure. But if you find that much easier said than done, then it’s important to seek additional treatment.

Related: CPAP Therapy for Sleep Apnea

Next Steps to See if Sleep Apnea is Impacting Your Blood Pressure

If you suffer from hypertension but aren’t sure if sleep apnea or another sleep disorder is a contributing cause, getting an evaluation to rule it out is important. Reach out to your doctor or a sleep expert to set up a sleep study and to explore your treatment options. The solution could simply be a consultation away.

If you’re unsure if your sleep-disordered breathing is caused by sleep apnea, check out our sleep quiz. If you’re ready to discover how a sleep specialist can help you, contact Sleep Centers of Middle Tennessee today to find out if sleep apnea is affecting your blood pressure.

With obstructive sleep apnea and high blood pressure having such a strong connection, a simple and free 10 minute sleep test evaluation may be the best thing you can do for your heart.

Sleep and high blood pressure have more in common than you may originally think— they affect each other to the point where seeking treatment for one condition may also end up treating another. Proper sleep and caring for your heart not only keep you healthy, but they keep each other healthy too!

References

“Facts about Hypertension.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 27 Sept. 2021, www.cdc.gov/bloodpressure/facts.htm. 

Guo, Xiaofan, et al. “Epidemiological Evidence for the Link between Sleep Duration and High Blood Pressure: A Systematic Review and Meta-Analysis.” Sleep Medicine, U.S. National Library of Medicine, Apr. 2013, www.ncbi.nlm.nih.gov/pubmed/23394772. 

Tochikubo, Osamu, et al. “Effects of Insufficient Sleep on Blood Pressure Monitored by a New Multibiomedical Recorder.” Hypertension, 1 June 1996, www.ahajournals.org/doi/full/10.1161/01.HYP.27.6.1318. 

“CPAP Rapidly Improves Blood Pressure and Arterial Tone in Adults with Sleep Apnea.” American Academy of Sleep Medicine – Association for Sleep Clinicians and Researchers, 23 Aug. 2017, aasm.org/cpap-rapidly-improves-blood-pressure-and-arterial-tone-in-adults-with-sleep-apnea/.

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